Electric switch



R. H. SCHMITT July 2, 1935.

ELECTRIC SWITCH Filed May 31, 1933 Il 'lllllllll lld llllll am ma Inventor:

Richard H. chmitt,

l'gjttorn ey.

' maintained Patented July 2, 1935 UNITED STATES ELECTRIC SWITCH Richard H.4 Schmitt, Schenectady, to General Electric Company,

New York N. Y., asslgnor a corporation of Application May 31, 1933, Serial No; 673,636

19 Claims.

My invention relates to electric switches of the type arranged to be operated with a snap action to open and closed circuit positions, and has for an object the provision of a reliable and inexpensive operating mechanism for a switch of this character which readily lends itself to mass production.

While not limited thereto my invention is particularly applicable to thermally operated switches for the control of fractional HP motors. Heretofore toggle mechanisms including an overcenter spring have been used to operate switch contacts to open and closed circuit positions. A thermal device associated with the toggle automatically opened the switch in response to a predetermined flow of current. However, much is yet to be desired in simplifying the construction of a switch of this character so that it can be readily assembled with or without an overload tripping device and as a single or double-pole switch. It will be further understood that the space factor is important and consequently the switch must be very compact so that its overall dimensions will be in keeping with the size of the motor it controls.

in carrying out my invention in one form thereof, I provide a switch arranged to be opened and closed with a snap action and to be opened automatically in response to a predetermined overload current. More specically, I provide a contact carrier with an inclined slot into which extends a sleeve supported on one end of an operating link. The other end of the link is fastened to a pivoted tripping far normally in a predetermined position by means of a thermal overload device. The contact carrier is operated between opposite extreme positions with a snap action by means of an overcenter spring having one end connected to the sleeve and the other end connected to an operating member. Upon the occurrence of an overload, the thermal device permits the tripping bar to move to a tripped position to open the switch.

For a more complete understanding of my invention reference should now be had to the drawing wherein I have shown in Fig. l a plan view, partly in section, of a switch embodying my invention with certain parts removed; Fig. 2 is a side elevational View looking in the direction of the arrows 2--2 of Fig. l; Fig. 3 is a side elevational view looking in the direction of the arrows 3 3 of Fig. l; Fig. 4 is an exploded perspective view, partly in section, of the switch mechanism; Fig. 5 is a plan view of the operating knob and its support; Fig. 6 is a sectional elevation taken on the lines 6 6 of Fig. 5; Fig. 7. isa perspective view, partly in section, showing the mounting means for one of the switch elepole switch provided with a (Cl. 20o-116) ments; while Figs. 8 and 9 illustrate my invention applied to motor controlling circuits.

Referring to the drawing, I have shown my invention in one form as applied to a doublepair of stationary contacts I and I I (Fig. 3) and cooperating movable contacts I 4 and I5, preferably made of silver. The stationary contacts I0 and lI are each rigidly secured against turning movement to a base I6 formed of insulating material by means of metallic insert moulded in the base, such for example, as the insert I8 provided for the stationary contact i0 and shown in detail in Fig. 7. The lower portion I 8a of the insert is knurled so that any tendency for the insert to turn is prevented. The upper portion 28cof the insert has its center drilled to form relatively thin side walls. The stationary contact member i0 has a base portion I Ila provided with an opening 20 of the same diameter as the upper portion [8c of the insert I8. In assembling the stationary contact i0, it is placed on the insert and the thin walls of the insert I8 are spun over against the base portion I 0a. The upper side of the base portion Illa is knurled around the opening 2li, as shown, so that the metal of the insert flows into the depressions formed oy the knurling, thereby locking the stationary contact iu to the insert i8 and to the base i6. The drilled portion of the insert I8 is also provided with threads so that a Contact screw 22 can be held in threaded engagement with the insert.

The movable contacts if and I5 are operated to an open and closed circuit position by means of a contact carrier arm 25 formed of insulating material and an operating mechanism 26. The contact carrier is pivotally supported upon a post 28 whichhas its lower end moulded in the base i6. Since the mountings for the movable contacts i4 and i5 are identical in construction, the mounting of only one, i. e., the contact it, will be described in detail. As shown the contact I4 is Welded to a double exible spring conductor 3l, preferably formed of `bronze, one end 35 of which is connected to a terminal 3i. The conductor 3l is normally held in spaced relation with the carrier 25 by means of a compression spring 34 mounted in a recess provided in the carrier. The other end of the conductor 3I lies in a slotl 36 and is provided with an enlarged or T-shaped portion 38 overlying the slot 36 to limit the outward movement of the conductor 3I by the spring 34. When the contacts are closed, the spring 34 is compressed and insures a good wiping action on the contacts, the T-shaped end 38 of the conductor sliding in the' slot as the spring is compressed. It will be understood that the other movable contact I is mounted on the double' conductor '4|' in exactly the same manner as described for the contact I4. As shown, grooves are provided on the carrier to prevent the conductors 3| and 4I from coming into engagement with each other.

It may here be observed that if the switch is to be assembled as a single-pole circuit breaker it is only necessary to omit the assembly of one of the contact members and its related spring.

Continuing with the description of my invention, the contact carrier 25 is operated on its pivot by means of inclined slots 44 andv 45 provided in a U-shaped metallic member 46 secured to the contact carrier 25. An operating link 48 for the contact carrier is provided with a pivot pin 49 upon which is rotatably mounted a sleeve 5U which lies in the inclined slots, and bears against opposite sides of the slots, or as shownagainst the opposite inclined plane surfaces formed by the slots, in moving the contact carrier to its open and closed positions. The opposite end of the operating link 48 is pivoted at 52 to a tripping bar 53. A U-shaped operating member 55 is provided having one arm 56 pivotally connected to the upper stationary plate 51 of a supporting frame by means of a pivot pin 58 secured thereto and extending through a hole 58a in the arm 56, the other arm 59 of the U-shaped operating member being supported in spaced relation with the lower plate 60 of the frame by the pivot pin 6I. The metal frame plate 60 is secured to the base I6 by means of screws and the frame plate 51 is secured to the plate 69 in parallel spaced relation therewith by means of the posts 64 and 65.

In order to operate the switch to open and closed positions with a snap action, an overcenter spring 1I! is provided having one end connected to the sleeve 50 and its other end connected to the mid-portion of a pin 12 secured to and extending between the arms of the U-shaped operating member 55. As shown, the overcenter spring 10 biases the operating link 48 for rotatlonfabout its pivot 52 in a counter-clockwise direction. An increased component of the force exerted by the spring 10 is thereby applied to the contact carrier 25 by reason of the engagement of .the sleeve 5B with the inclined slots 44 and-45 to bias the movable contacts against the stationarycontacts. Since this component of force applied to the contact carrier 25 rapidly increases as the sleeve 50 moves from an open circuit position lto the closed position shown in Fig. 1, any tendency of the contacts I4 and I5 to rebound is effectively prevented. It will be observed that by operating the member 55 from the position shown in Fig. 4 in a counterclockwise direction, the pin 12 is carried beyond the dead center position located at the pivot 52. Just as the spring reaches the dead-center position the component of force exerted by the spring on the operating link 48 is reduced to zero. Consequently, at this moment the only forces applied to the contact carrier are due to the springs 34 associated with the contacts I4 and I5. The contact pressure is not diminished since the slots 44 and 45 and the link 48 are so arranged that no movement of the contact carrier occurs due to the forces exerted by the wiping springs 34. This is due to the fact that, as will be observed from Fig. l, a line extending from the center of the pivot pin 52 `to the point on the sleeve 50 engaging the slot 44 forms an obtuse angle slightly greater than a-right angle with the side of the slot engaged by the sleeve. Consequently, an insufcient component of force is exerted by the spring 34 on the operating link 48 to move it along the slot. The contact carrier is thus eiectively locked in the closed position. However as soon as the overcenter spring goes beyond this dead center position the operating link 48 is rotated in a clockwise direction to apply an increased component of the force of the spring against the slots 44 and 45 to operate the carrier to open the switch.

If the slots 44| and l5 were not inclined with respect to the radius of the operating link 48, only a relatively small force would be available to maintain the contacts in their closed position. In accordance with the invention, however, an increased force exists to close the contacts against the opposing bias oiered by the compression springs 34. Besides multiplying the force of the spring 1G, the obtuse angle formed by the slots and the link 48 minimizes the initial friction existing between the sides of the slots and the sleeve so that a faster movement of the contacts is secured, although as previously stated the angle is such that the spring 34 cannot initiate the movement of the contacts.

An extension 86 of the pin 12 engages the upper frame plate 51 at points indicated by the curved recesses 86a and 86h and thus limits the movement of the operating member 55 between predetermined extreme positions. The operating member 55 is manually operated by means of a knob formed of insulating material and loosely connected thereto. It will be observed, Figs. 2, 4, 5 and 6, that the knob 80 is supported in a metallic plate 82, the knob being provided with a recess 84 into which the end 86 of the pin 12 extends. The recess 84 is larger than the end 86 of the pin 12 and provides a lost motion connection with the pin. Consequently, the spring 10 is free to move the operating member in the recess independently of the operating knob 80. If this connection were not provided, it might be possible to turn the knob 80 until the dead center position were reached, at which point the component of force exerted by the spring on the operating link 48 would substantially diminish. By reason of the lost motion action, however, the spring cannot be held in its dead center position. If the switch is either being opened or closed, the spring is powerful enough to cause the operating member 55 to exert a hammer blow on the knob 80 by reason of the lost motion connection between the knob and the member 55. This hammer blow is of suiiicient strength to operate theswitch from one position to the other irrespective of the will of the operator.

The construction of the knob 80 is shown in Fig. 6 and comprises two members 90 and 9| secured together by a metallic insert 92 moulded integrally with the member 99. One end 93 of the insert 92 extends through the other member 9| and is spun over against it. The upper portion has an annular flange 95 which rests against plate 82 and an annular central portion which extends through the opening provided in the plate 82. The outer end 96 of this central portion is rectangular. The member 9| is provided with a recessed portion 91 of rectangular shape arranged to receive the rectangular end 96 of the upper member 90 so as to lock the two members 90 and 9| together. The dimensions are so selected as to permit the free movement of the knob 80 in the plate 82, between Cir two extreme positions determined by the engagement of a projection 90a on the knob with the plate at points indicated by the recesses 82a and 8227.

Continuing with the operation of my invention, it will be observed that the tripping bar 53 is pivotally mounted at one end to the post 65 provided with a sleeve 65a on one side of the bar and a washer 65o on the other side or" the bar, the sleeve and washer xing the position of the bar 53 on the post. The tripping bar is maintained in the position shown in Figs. l and 4 by means of a latching member 99 secured to the tripping bar 53 and cooperating with a thermal overload device |00. The thermal overload device |00 comprises a gear |0| supported by a sleeve |02 surrounding .a stationary post H03 moulded in the base I6. The gear lill is normally maintained stationary by reason of a solder lm connecting the sleeve |02 to the post |03. A heater coil surrounding the sleeve |02 is energized in response to the current flowing through the switch and upon-the occurrence of a predetermined overload causes the solder film to melt, thereby releasing the gear |B| for rotation.

inasmuch as the operating linlr' is pivoted to the tripping bar 53 the force of the overcenter spring '|0 tends to rotate the tripping bar in a clockwise direction about its pivot 65 as viewed in Fig. l. Normally the tripping bar 53 is maintained in its normal position shown in Figs. 1 and 4 but as soon as the gear li is free to rotate, the tripping bar 53 rotates in a clockwise direction. inasmuch as the contact operating sleeve 50 moves with the tripping bar it will be observed that the sleeve operates the contact carrier to the open circuit position.

In order to reset the tripping bar 53, the knob 80 and the U-shaped operating member 55 are rotated in a counter-clockwise direction. Duringthis movement a notched end i i@ provided on the arm 59 of the U-shaped member 55 engages an upturned projection H2 provided on the tripping bar 53 so that the tripping bar is rotated in a counter-clockwise direction. When the operating member 55 reaches the limit of its movement the tripping bar is in its normal position with the latching member engaging the teeth of the gear lili. Since the operating knob is now in the orf position, it will be observed that the mechanism. is trip free. That is to say, the knob 8@ even though operated cannot maintain a closed circuit ii a current exists of suflicient magnitude to release the gear |0| because the tripping bar 53 must be in its normal position before the switch can be closed.

fis l have stated, my invention is particularly applicable to the control of fractional HP motors. A large majority of motors of this type is designed to be operated either on 110 volts or 220 volts, a change from one to the other voltage being made by connecting the motor windings either in series or in parallel. Heretofore, heater coils have been provided for the particular voltage with the resistance of the coil proportioned for the particular voltage for the particular source of supply.

In accordance With the single heater coil |05 can be used for either 110 volts or 220 volts by reason of a double terminal member ||5 provided with terminal screws, one of which secures one end of the heating coil |05 to the terminal member ||5. Referring now present invention the to Fig. 8 it will be observed that the line terminals 22 and ||8 of the switch are connected to the 22o-volt supply lines |20 and |2l. The terminal 22 is connected to the stationary contact |0 while its cooperating movable contact I4 is connected to a terminal member 3l. The movable contact I5, cooperating with the stationary contact connected to the terminal H0, is connected to the double terminal member H5. The other end of the heater coil |05 is connected to a terminal member 28. The motor windings and 3| are connected in series with each other and are connected to the switch by means of the terminal 3l and the terminal |28. With the movable contacts I5 and |5 in the closed position the current lows from the supply line |20, by terminal 22, contact |0, movable contact I4, terminal member 3l, motor windings |30 and itl, terminal mem ber |28, heating coil 105, the double terminal M5, movable contact i5, stationary contact il and from the terminal l I8 to the other supply line l2|.

In case the switch is to be connected to a llO-volt source of supply, the motor windings E30 and |35 are connected in parallel as shown in Fig. 9. The supply lines and lll! representing the 11G-volt source of supply are connected to the terminal members 22 and H8. Common sides of the motor windings 30 and ISG are connected to the terminal 3'5 while the opposite side of the motor Winding 530 is connected to the terminal H5. lThe opposite side of the motor winding iti is connected to the terminal 52S. In this case it will be observed, with the switch in the closed circuit position, that the current rlovfs from the supply line Mo by terminal 22, stationary contact i0, movable contact lo, terminal member 3l, and divides through the motor windings i351 and 33. The current plowing through the motor winding it returns to the supply line iti by terminal member i226, heating coii movable contact stationary contact ii and the terminal member il@ while the current flowing through the motor Winding l is bypassed around the heater coil by reason oi the direct connection of the double terminal to the movable Contact Consequentiy the current owing through the heating coil is the saine for either the or the 22o-volt source or" supply.

it is to understood that the improved tening means described for static' tacts is also used for the terminal 'Each terminal member is integrally the oase it? by means a metallic ins ed to the base and having its end against its terminal member in the sam manner as described in detail for mounting y stationary contact l viding a plurality oi ridges and depressions is provided` adjacent the insert so that the metal flows into the depressions and prevents the terminal members from turning about their respective inserts.

In case it is desired to assemble the switch without the use of the thermal overload device |00, it is only necessary to insert a screw in the threaded opening (Figi) provided in the base plate 60, the upper end of the screw being long enough to engage the tripping bar 53 to hold it in its normal position. The switch can then be operated as a conventional snap switch.

If a single-pole switch is desired it is only necessary to assemble one of the spring contact A knurled surface promembers on the contact carrier, the other parts of the switch remaining the same as for the double pole breaker. Itwill therefore be seen that the identical switch members can be used for single-pole or double-pole switches or for switches with or without thermal overload tripping devices.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. In a. switch, a switch member provided with inclined plane surfaces, and operating mechanism for said switch member provided with means operable between predetermined positions with a snap action and alternately engaging said surfaces to operate said switch member between open and closed circuit positions with a snap action.

2. In an electric switch, a switch member provided with inclined plane surfaces, operating mechanism for said switch member provided with means operable between predetermined positions with a snap action for alternately engaging said surfaces to operate said switch member between open and closed circuit positions with a snap action, and overload means associated with said mechanism for operating said switch member from said closed position to said open position.

3. A switch mechanism comprising a switch member movable to open and closed positions said switch member being provided with an inclined slot, an operating link having one end slidably engaging said slot, a pivot for the other end of said link, an overcenter spring operable between predetermined positions for rotating said link in opposite directions about said pivot so as to apply the force of said spring to said switch member to operate it to said open and closed positions.

4. A switch mechanism comprising a` switch member operable between open and closed circuit positions provided with a pair of inclined surfaces spaced apart one from the other, an operating link one end of which cooperatively engages said inclined surfaces, a pivotal mounting for the other end of said link and an overcenter spring for rotating said link in opposite directions about said pivotal mounting to operate said switch member between said positions with a snap action.

5. A switch mechanism comprising a switch member movable to open and closed positions, said switch member being provided with an inclined slot a tripping bar movable from a normal position to a tripped position, an operating link having one end pivoted on said tripping bar and the other end slidably mounted within said inclined slot, an overcenter spring for rotating said operating link about its pivot to operate said switch member to said open and closed positions and for biasing said tripping bar to said tripped position and thermal responsive means for maintaining said tripping bar in said normal position.

6. A switch mechanism comprising a switch member movable to the open and closed positions, said switch member being provided with a slot, an operating arm having one end slidably .ber when in said closed position and to lock said switch member in the closed position.

7. A switch mechanism comprising a switch member movable to open and closed positions, said switch member being provided with an inclined slot, a tripping bar movable from a `normal position to a tripped position, an operating link pivoted at one end to said tripping bar and having its other end slidably engaging said slot, an operating member, an operating knob therefor loosely connected to said member, an overcenter spring connected to said operating link and to said operating member for rotating said link to operate said switch member to said open and closed positions, said loose vconnection permitting enough relative motion between said operating member and said knob to permit said overcenter spring to move past its dead center independently of said knob, and a thermally responsive means for holding said tripping bar in said normal position.

8. A switch mechanism comprising a contact carrier, an overcenter spring for operating said carrier to open and closed circuit positions, said carrier being provided with a groove along one side thereof, Aa flexible conductor mounted in said groove and having a projecting end extending to the opposite side of said carrier and a compression spring normally biasing said conductor away from said carrier.

9. An electric switch provided with relatively movable contacts, a contact carrier provided with a depression at one side thereof, a exible conductor extending from one side of said carrier through said depression to the other side of said carrier,l said end of said conductor being provided with an enlarged end for engaging said carrier, a compression spring between said conductor and said carrier for normally biasing said enlarged end against said carrier and an overcenter spring for operating said carrier to open and closed circuit position with a snap action.

10. An electric switch provided with a base formed of `insulating material, contact terminals secured to said base at opposite ends thereof, a contact carrier pivotally mounted upon said base, an overcenter spring connected to one side of said carrier for operating said carrier to open and closed circuit positions, movable contact members comprising resilient electrical conductors having one end fixedly secured to said terminal members said Vconductors extending from said terminal members along one side of said carrier, the opposite ends of said conductors extending from said one side to the other side of said carrier and a compression spring mounted between said conductors and said carrier for normally maintaining said conductors in spaced relation with said carrier, the other endsV of said conductors being arranged to engage said carrier.

1l. An electric switch provided with a base of moulded insulating material, a metallic insert moulded integrally with said base and having an end extending above said base, a switch so that when said end of said insert is spun over against said switch member the metal flows into said depressions to secure rigidly said switch member to said insert.

12. An electric switch provided with a moulded insulating base, a metallic insert `moulded integrally with said base and provided with a projecting end, a stationary contact provided with an opening for receiving said end of said insert, the area surrounding said hole being knurled to form a plurality of depressions into which metal can ow when said end of said insert is spun over against said stationary contact thereby locking said stationary contact to said insert and to said base.

13. An electric switch provided with an insulating base, a pair of stationary contacts, a pair of load terminals secured to onel portion of said base and connected to said stationary contacts, a pair of movable contacts, means for operating said movable contacts between open and closed circuit positions, thermal responsive means for operating said contacts from said closed circuit position to said open circuit position, a plurality of load terminals, connections for connecting one of said terminals directly to one of said movable contacts, connections for connecting said other contacts in series with each other and with said thermal responsive device and said other movable contact whereby said switch can be connected to sources of supply having different values of voltage without changing the adjustment of said thermal responsive device.

14. An electric switch provided with a supporting base, a pair of stationary contacts for said switch, a pair of movable contacts, means for operating said movable contacts into and out of engagement with said stationary contacts with a snap action, a thermal overload device for operating said contacts from a closed circuit position to an open circuit position, line terminals provided on one portion of said base and three load terminals provided at the opposite end of said base said overload device being connected in series with two of said terminals and with one of said stationary contacts and one of said movable contacts, the other of said load terminals being connected to the other of said stationary and movable contacts whereby said switch can be connected to either of two voltages without changing the characteristics of said overload device. i

15. A motor starting switch for a motor provided with a pair of field windings, line terminals for said switch, cooperating contacts operable to open and closed circuit positions,` operating means for said contacts, thermal responsive means for operating said contacts from said closed circuit position to said open circuit position, a heater coil for said thermal responsive means, three load terminals supported by said base, connections for connecting one of said terminals in series with one of said stationary and movable contacts, connections for connecting two of said load terminals in series with each other, said heating coil and said other movable and stationary contacts whereby said motor windings can be connectedfin series with each other and to two of said terminals; said, heater coll being included in said series circuit and so that 'said motor .windings can each be connected to a pair of said terminals so that said heater coil is connected only in series with one of said windings.

16. A switch comprising a movably mounted switch member provided with a pair of plane operating surfaces, an operating member for said switch member, and means mounting said member for movement between predetermined positions in a constrained path extending at an angle with said surfaces and for sliding engagement with said surfaces alternately to operate said switch member between open and closed circuit positions.

1'1. A switch comprising a movably mounted switch member provided with a pair of parallel operating surfaces, an operating member for said switch member slidably engaging said surfaces, means mounting said operating member for movement between predetermined positions in a constrained path extending at an angle with said surfaces, and spring means for moving said operating member with a snap action between predetermined positions to operate thereby said switch member between open and closed circuit. positions. l

18. A switch mechanism comprising a switch member movable to open and closed positions, said switch member being provided with an inclined slot, an operating link having one end slidably engaging said slot, an overcenter spring operable between predetermined positions for operating said link in opposite directions so as to apply the force of said spring to said switch member to operate it to said open and closed positions, a tripping bar biased for movement from a. normal position to a tripped position, overload responsive means retaining said tripping bar in said normal position and operable on overload to release said bar for movement to said tripped position, and connections between said tripping bar and said operating link for operating said switch member from said closed position to said open position upon movement of said tripping bar from said normal position to said tripped position.

19. A switch comprising a switch member movable to open and closed positions, said switch member being provided with an inclined slot, an operating link having one end slidably engaging said slot, pivot means for the opposite end of said link, an over-center spring one end of which is connected to said link, an operating handle connected to the opposite end of said over-center spring for moving said spring with reference to said pivot means to rotate with a snap action said link in one direction or the other, said link and said slot applying the force of said spring to said switch member to operate it to said open and said closed positions, a tripping bar biased for movement from a normal position to a tripped position, overload responsive means retaining said tripping bar in a normal position and operable on overload to release said bar for movement to said tripped position, said tripping bar operably connected to said operating link for operation independently of said handle of said switch member from said closed position to said open position as said tripping bar moves from said normal position to said tripped position, and means operable by said handle for returning Vsaid tripping bar to said normal position prlorto the return of said switch member to said closed position.

RICHARD H. SCHMITT. 

